The invention relates generally to area array socket connectors and particularly to a land grid array (LGA) socket connector.
Competition and market demands have continued the trends toward faster, higher performance electrical systems, particularly with regard to computer systems. Along with the development of surface mount technology in the design of printed circuit boards, higher density electrical circuits, including higher density interconnect components have been developed to meet the increasing demand for higher performance electrical systems.
As is known in the art, surface mountable packaging allows for the connection of the package to pads on the surface of the circuit board rather than by contacts or pins soldered in plated holes extending through the circuit board. As used herein, the term “package” shall refer to a chip carrying module that is to be mounted to a circuit board. Surface mount technology allows for an increased component density on a circuit board, thereby saving space on the circuit board.
Area array socket connectors have evolved, along with surface mount technology, as one high density interconnect methodology. One significant application of this technology, for example, is the land grid array (LGA) socket connector that is used with an LGA package. One major advantage of the LGA package lies in its durability. The LGA package is not easily damaged during the installation or removal process or by handling generally. At least some of the other IC packages, such as a pin grid array (PGA) package, have a standardized layout, or form factor, for contact leads or pins on the package. These contact leads are somewhat fragile and can be damaged if not handled properly. By contrast, with an LGA package, there is nothing protruding from the package that can be bent or otherwise damaged during normal handling.
The LGA package includes an array of contact areas or pads on an underside thereof. The LGA package is typically loaded into an LGA socket which establishes electrical continuity between the LGA package and the circuit board.
Typically, the LGA socket includes an array of contacts and the circuit board includes a pad pattern or contact pad array that both correspond to the contact array on the LGA package. Generally, the LGA socket contacts each include a solder ball pad and a solder ball for mounting to the circuit board and a contact tip for mating to the LGA package.
When loaded into the socket, the LGA package registers on the interior side walls of the socket. To assure proper electrical continuity between the LGA package and the circuit board, the solder balls on the socket contacts must also be registered to the socket side walls. Presently, the solder balls are referenced to a socket side wall, however, there is no way to visually inspect the position of the solder balls relative to the socket side walls.